A large number of the electric power converters, that is, inverters and converters are lately in use in the respective fields of energy conservation and new energy, however, in order to realize a low-carbon society, a marked increase in prevalent use thereof has become indispensable.
With the electric power converter, power conversion is executed by turning the semiconductor switching element ON-OFF. For the semiconductor switching element, much use is made of an IGBT (Insulated Gate Bipolar Transistor) as one type of power semiconductor element. With the semiconductor switching element such as the IGBT, etc., power dissipation occurs at the time of conduction and at the time of switching, respectively, and it is therefore necessary to reduce the power dissipation occurring to the semiconductor switching element in order to achieve miniaturization of the electric power converter, or higher efficiency thereof.
There has been proposed a double-gate semiconductor switching element provided with two units of gate electrodes (refer to Nonpatent Literature 1, and Patent Literature 1), representing a technology capable of reducing both conduction loss and switching loss. With the double-gate semiconductor switching element, a control signal is imparted to one of the gate electrodes to switch over from an IGBT operation mode to a thyristor operation mode, and vice versa, thereby reducing both a conduction loss and a switching loss.